The problem some had with the appearance was the idea that neither Jason nor Tim could ever get along. This idea came from stories like Battle for the Cowl, the Teen Titans Countdown tie in (*1), and maybe one other appearance I'm forgetting about. Which confuses me because those weren’t really true to the characters, books that always were questionable canon and even more so now. Regardless of what is considered canon having Jason and Tim get along isn't as out of the blue as some claim.
They first met (*2) in Hush when Jason has a knife on Tims’ throat. No, Jason isn’t too friendly with Tim but then again it wasn’t really about him. Tim is simply a prop to get Bruces’ attention. The whole purpose of this “face time” was to prod Bruce to see how he felt about Jasons’ death. To try to get a rise out of him. No, the time it’s about Tim is when Jason visits him at Titan tower (*3) and uses it to test him with a fight. Even here Jason doesn’t hate Tim. Why? Because although he defeats him Jason doesn’t kill him and ends up respecting him. Jason wonders if things would have been different if he had friends.
But let's think about Tim. Does anyone remember how he became Robin in the first place? He was a fanboy of Bruce, Dick and yes, Jason. I'd say that Jason arguably cast a bigger shadow on Tims' role as Robin than Dick did. Under Chuck Dixon Tim admits to Dick that he thinks about "the other Robin" all the time. Sadly most writers have forgotten this once Jason came back, some never mention it. The only one that does is Geoff Johns who has Tim correct Jasons' impression that he was forgotten. "No one could forget you."
With the exception of Damian (who was given the role of Robin without Tims' consent) and Captain Boomerang (who killed his father) Tim doesn't really hold grudges. He doesn't always follow Bruces' orders either. This is a Robin that under Johns admits he lies to Batman. That worked with Huntress when Batman seriously disapproved of her and her methods. (Long before she was part of BOP.) He’s willing to work with shades of grey. In the “Search for a Hero” arc in Robin both boys show an interest in helping each other out. Admittedly Tim isn’t always in the best of moods but then again he was going through a lot. Bruce just “died”, he lost his father, found out his (ex) girlfriend faked her death and she's lying to him to carry out Bruces' wishes. So he’s a little moody but he’s the one Jason reaches out for.
Jason sees that Tim might be a little more flexible than Bruce or Dick and while Tim rejects his offer to join forces he does get inspired by Jasons’ idea. He knows the plan has cunning and adapts it.
Tim sees the potential in Jason to be more than what he currently is and does something no other bat member has done since he came back--he not only gives him a chance but helps him out.
At the cave Tim is colder than he was visiting Jason in jail but a lot has happened. (He sort of got two kids killed.) Lost in his own thoughts the usually perceptive Robin doesn’t seem to pick up on the fact Jason IS trying to reach out again. Jason asks what happens now and when Tim doesn’t give a positive response he retreats again. I know Johns has Superboy ask why Tim chose the Red Robin costume since it belonged to “the bad Robin” and Tims’ odd answer. But I don’t buy it. Why would Tim keep it after Bruce comes back if he simply needed space from the rest? No, it has to be more than that. Tim had to have kept it for another reason since it was so closely linked to Jason. Perhaps because Jason did use it when he briefly considered returning to the spandex set? Maybe although it’s likely a moot point in the relaunch.
Others have stated that since Winick is the one who brought Jason Todd back as Red Hood he knows the character better than anyone. Winick has said that he believes Jason hates Tim more than Dick. But here's the thing: Winick has NEVER written the two together. At most he has Jason reacting to the news he's been replaced and a drugged Bruce mistaking Tim for Jason. That's it. So in my opinion nothing he says that he hasn't written can be taken as canon anyway. What he did write was Jason going out of his way to tell Dick that Black Lightening was innocent of murder. There’s nothing to be gained in sharing this information. Jason arranges for the meet and actually tries to get Dick to listen to him. It’s Dick that starts attacking and while Jason could have ended their match by shooting him, he doesn’t. He admits that he doesn’t want to do it just pass the information on. Being good at getting intel and willing to share it is something Scott Lobdell uses in RHATO.
Now it’s obvious from the way Jason and Tim greet each other in RHATO that this isn’t their first meeting on good terms. Their civil but Jason is still sarcastic. Like the meeting between Jason and Dick Winick wrote in Outsiders Jason flippantly calls Bruce “dad” only adding a “bro” when referring to Tim. This is calmly countered by Tim who says that legally Jason is dead which might void that. But above all else this is a business meeting. It’s a information exchange. Neither owes the other anything with such an arrangement. It’s on equal footing. The fact that Jason is ready to leave after he gets what he needs only proves that while they aren’t fighting anymore this was only business.
It’s Tim that tries to get them on more friendly terms. Why wouldn’t he if they have been doing this for awhile and have been getting along? They obviously earned enough trust to carry on these meetings for awhile. Still Jason cares what will happen to Tim in regards to his relationship with Bruce. He knows their contact isn't something the big guy would approve of. At least that can be argued as a simple need for information. But being nice to Jason? He knows how much Robins want Batmans' approval and how it hurts when you don't have it. Plus he feels bad for how he treated Tim in the past. Tim on the other hand has always been more of a loner as Robin. He's on his own more and doesn't need to check in to get an okay. Tim points out that Bruce isn't there because this isn't about him. It's about them. That's good insight on the characters and actual development in my book.
The fact that it’s Tim makes the most sense out of all the batmites that know Jason. While Barbara might understand how it felt to be harmed by the Joker this Barbara is still developing. If she’s anything like she was as Oracle she is anti-gun. Tim is more open. In Teen Titans he’s even discussed the idea of killing someone and has killed in a fake psychic set up. I’m impressed that someone understands Jason was trying to cope with everything that happened to him. (The closest we got to anyone saying the obvious, that Jason suffers from PTS.) But Tim also gets that the others don’t understand that. I for one am pleased with this. Not only does Jason have positive contact within the family but it makes part of the bat family more likable for finally trying to reach out to Jason. I'd take this over Battle for the Cowl version every time.
*1 It seems likely that Countdown isn’t canon anymore since none of the Crisis happened. Not that Final Crisis treated it as canon anyway. BFTC really wasn’t needed to explain how Dick becomes Batman. Not only is some of the cast out of character but it only confuses some things. Jason acts like a nut when he was calm and collected in the final scenes of the Robin arc leading up to this. Damian acts like a coward. Oracle is an idiot that ejects a girl out of the batmobile leading to the girl getting killed by Killer Croc. Also, Tim grabs Jasons’ Red Robin costume after this? Did Daniels know that at the time? Just saying it doesn’t seem to fit.
*2 Not sure if this is canon since Clark/Lois and Selina knowing who Bruce is doesn’t exist anymore. But I’m assuming it is at present.
*3 Another uncertain meeting as Tim is just starting out as a TT and the team it’s self is new in DcnU. A big point of it was Jason being mad that no one remembered him and that he was a titan (for some reason he didn’t have a statue like other dead titans did.) Although the idea of Jason fighting Tim could still be canon since Jason mentions he “wasn’t the nicest guy” to Tim.