In the three-volume manga Shin Kidou Senki Gundam W Trowa is quite different as is Quatre in the beginning.
Volume 1:
Trowa first appears on page twenty-one in the first volume. He is in Heavy Arms destroying Leo Mobile Suits at the UESA Space Port. Quatre is introduced after him and is located in Africa battling the UESA Desert Forces Troop.
They eventually meet at New Edwards Base in Los Angeles. All five Gundams are there and they notice they are all fighting the Alliance. Quatre wonders if they are all on the same side then. Trowa responds he"s on no one"s side. Trowa is far more leery of others and quite blunt here, yes?
Still, when Trowa runs out of ammunition, Quatre offers to help. He introduces himself and his Gundam. Trowa is still leery and says, "Thanks, but I don"t need help." Quatre is not deterred though. He reasons to Trowa why they should work together and eventually Trowa notes what he says is true and warily provides his name. Quatre is happy with such and says it is good to meet him.
After they finish demolishing the Mobile Suits at New Edwards Base, Quatre believes by then they can"t be enemies. The others, Trowa included, aren"t to sure though and readies there weapons. Quatre of course tries to stop them. Wu Fei realizes the five of them were duped and ends their dispute.
Volume 2:
The next time Trowa meets Quatre is in the second volume, page thirty-two. The settings are the same as in episode twenty-four in the anime. Heero and Trowa approach a ZERO System controlled Quatre who is destroying OZ suits in space.
Trowa is not leery of Quatre anymore as he notes it must be Quatre in the Gundam before them. He asks Heero about joining him. Heero cautions since they don"t know the pilot"s angle even if it is Quatre. Thus, Trowa flies up to the suit and checks. When it is established Quatre is the one piloting, Trowa relaxes and smiles. He tells the other it is good to see him, but soon Quatre fires his twin buster rifle at him.
Trowa is shocked and dodges only to have the right arm of his Vayeate blown off. He cries out what is wrong with the other and tells him it is him, Trowa. Quatre then tells him his mission. Trowa can only look at the other with widen eyes and stutters on the first word of his question, "W-What"s wrong with you, Quatre?"
Quatre then warns Trowa to tell the others to keep away or he"ll kill them too. Trowa is solemn and begins to talk but Heero interrupts by attacking Quatre. They fight and eventually Quatre shoots his twin buster rifle at Heero. Trowa, like in the anime, takes the blow instead shocking Quatre.
The main difference here though is they converse rather than Trowa giving a monologue. Another thing is, it is uncertain if Quatre hears Trowa through his Space Heart or not. It seems to be that... In any case, their dialogue is the following:
"Quatre... you are too kind a person for this life. Don"t force yourself to do something you"ll regret. You no longer have to be alone."
"Oh, Trowa... I"m so sorry. I made a mistake I can never be forgiven for."
Quatre is crying through this and clutching his heart. He is himself. Right after this part though, the Vayeate explodes. Heero tries to contact Trowa, but receives nothing. Instead Quatre speaks up. He leaves Wing Zero and asks Heero to kill him for he feels he doesn"t deserve to live.
Thus, from this, their connection seems to be stronger and deeper. They communicated through spirit. If one notices Trowa"s line, one might note how he said Quatre no longer has to be alone. Fans of the pairing of the two might see it as him telling Quatre that he will be the one to make Quatre not be alone. He is the one there. On the other hand, Trowa could have simply meant all the Gundam Pilots can sympathize and will be there for him.
Well, once Trowa disappears, Quatre actually wishes to die because of it. In the anime he demands Heero to go after Trowa to save him. Both shows Trowa is important to him, but it seems to be expressed greater in the manga. Then, when you consider it, in the anime he does note that if Heero has to kill him, to do such so he can then go to save Trowa.
The scenarios are still relatively the same though. The main difference is the hope in Quatre"s heart. In the anime he had hope that Trowa stood a chance. In the manga he was sure Trowa must have died.
Anyway, after Quatre"s request, Heero more or less tells Quatre he understood. Heero leaves his Mobile suit with gun in hand. Quatre then closes his eyes expecting Heero will kill him. He quietly tells Trowa and his father he will join him soon. He is surprised though when Heero reaches him. Heero seems to have fainted, but there is a possibility he hugged Quatre. I think it is the former. Quatre holds him and says, "I see... I... no longer have to be alone. Right, Heero?"
In any case, he took Trowa"s words to heart. Whatever Trowa meant, Quatre took it to mean he has all the other Gundam Pilots still.
It is later does Quatre shows he has hope. On page eighty he looks up Trowa"s whereabouts himself. In the anime others were the ones to look him up.
On page 128, Noin notes to Quatre that Trowa has been found in the L3 Colony Sector. Quatre responds, "Really? Trowa"s alive... I"m so glad."
While his look is possibly relief, there is the slightest hint of a blush on his cheeks. Also, as far as I am concerned... he kind of looks euphoric. Still, that is just from personal perception.
Soon Noin informs him there is a small problem. Quatre"s expression soon turns to concern and darkens. After she tells him Trowa has amnesia Quatre cries out how it is his entire fault and that he must go see Trowa.
Quatre arrives on L3 and enters the circus Trowa is with on page 132. He cries out the other"s name in joy and relief when he sees Trowa. Quatre has tears in his eyes and that blush is less faint on his cheeks when he does this.
He goes up to Trowa, puts his hands on his shoulders and babbles out how he is so happy to find the other alive. Trowa pulls away though and sadly doesn"t remember the other. Hearing such doesn"t deter Quatre a bit though. Instead he tells Trowa how he must come with him. He assures the other he will get his memory back. All of this is said with Quatre still having a blush on his face.
Before he can say more, Catherine comes in crying out no. She looks nervous and scared at the prospect of Trowa leaving. There are marks similar to a blush, but where they are positioned and how they are drawn indicates more of a look of distress rather than a blush.
Anyway, like in the anime, Catherine steps between them and pushes Quatre away from Trowa. She yells at Quatre that Trowa is her family and she"s not letting him go anywhere with a stranger like Quatre. Soon she realizes he must be a Gundam Pilot and tells Quatre she won"t let him hurt her "brother".
Hearing the word Gundam though sends a feeling of vague remembrance through Trowa. He decides to go with Quatre. He goes because he wants to regain his memories and because a part of him knows his presence is important - that there is more at stake than just his mind"s state.
So, in this scenario his decision had nothing to do with Quatre like in the anime and there is no indication of an emotional pull to him. He didn"t feel "[Quatre] crying."
Later Quatre picks up Duo and Wu Fei as well. They too are informed of Trowa"s amnesia. Wu Fei notes that "a true warrior will find himself in battle." Quatre feels Trowa is in no condition to fight though and says they must protect Trowa for the time being. So, while Wu Fei thinks Trowa is capable as he is, Quatre wishes to protect the other... A regular reader will see it as the contrast of personalities. Fans of the romantic pairing of Trowa and Quatre might see it as Quatre caring about Trowa deeply and thus will not take the risk.
Well, soon after Wing Zero, piloted by Zechs Merquise, shows up. Just seeing it makes Trowa uneasy. When hearing its name he suddenly panics. Trowa begins to tremble; he shows utter fear and his hands reach up towards his head.
Duo and Wu Fei take action and go out to face Zechs in their Gundams. Before Duo leaves he tells Quatre to take care of Trowa. By then Trowa is holding his head and wincing. Quatre is kneeling down, and holding him.
Pretty much nothing can be determined from this scene. Oh well...
Volume 3:
On page eighteen the Gundam Pilots go out to defend the Sanc Kingdom from attack. Trowa decides to follow, but Quatre still worries about is lacking memories. Trowa tells him not to worry, he won"t push himself and he says he"ll be Quatre"s backup.
Some might notice Trowa decided to be Quatre"s backup in this battle. Why did he pick Quatre? He could have offered working as back up to the other four pilots. Perhaps it was simply because Quatre was the first he met as far as his amnesia told him. Maybe he noticed how concerned Quatre is for him and thus trusts him the most. Maybe he feels more at ease with Quatre. Either way, he seems quite inclined to trust the blonde.
In volume three, page eighty-two, an amnesic Trowa winds up in a situation where he is surrounded by enemy Mobile Dolls. Quatre sees him in trouble and shields him. Seeing the familiar scenario, Trowa begins to remember. The words he told Quatre are said as he regains his memories.
Once it is over, he holds Quatre steady and more or less asks him if he is okay. Quatre notes Sandrock"s less than perfect condition but says it is okay as long as Trowa is in one piece. Trowa smiles at that and responds that so far Quatre has saved his life twice. I suppose he is referring to their first meeting when he ran out of ammunition. He finishes by saying he needs to start paying Quatre back. Quatre realizes then that Trowa"s memories are back and of course is delighted.
The significance in this scene is noted when compared to how Trowa got his memories back in the anime. It was mainly due to Wing Zero"s system messing with his head and Quatre saying words that triggered his memories. Here, though, it is all Quatre.
At the end of the manga, in volume three, is quite different from the anime. In the anime you can already assume where the Gundam Pilots went later on. Heero would continue fighting where he could, Duo would return the to scrap yard, Trowa would return to the circus, Quatre would run his family"s business and Wu Fei would do his own thing.
This is not the case though. Military bases from the war were put to use for space-based development. In one of those facilities a colonization research and development team was about to leave for Mars. That group is displayed on page 161. It is the five Gundam Pilots.
Now, while it is fishing, some might notice Trowa and Quatre are in the same attire while the rest are more or less in their usual garb throughout the series and manga. Perhaps they are dressed differently because they are at more corporative positions than the others. Still, it is interesting. Quatre sure... but it seems like Trowa followed him in terms of choosing his position.
Another silly thing to consider is the matching couple concept. Although it is rare and a faux pas in terms of fashion, there have been times in manga where such occur or are mentioned. "Couple wear" is what it is more or less called. Standing together and the only ones in matching attire... it sort of looks like such. Still, it is likely due to work uniform.
In any case, what their relationship is and what it can amount to is unknown. Like in the anime series, they do not seem to have anything between them that goes beyond friendship. Still, they do have a unique closeness that tends to be seen more between characters that are male and female pairs. If anything is deduced from the Shin Kidou Senki Gundam W manga is that Quatre seems to express his fondness for Trowa more than in the anime.