post-s7 Soren and Terry is very important, I think, because they both offer unique Things to each other as individuals and as a dynamic.
Soren gets someone who is unconditionally openly appreciative of him ("I really needed that today") versus Corvus who tends to be much dryer/reserved and Ezran, who's a potential swirling storm of distance and teenage angst. Terry gets someone who will unequivocally stick up for him and trusts him immensely, and will always keep Terry in the loop (tying into being part of Ezran's council being something that affords Terry agency and redemption, two things he cares a Lot about having and contributing to, and currently arguably culminating in him naming Evrkynd). They both get someone who understand what it's like to realize you're on the wrong side and went along / were actively or complicit in doing terrible things, and trying to come back from that.
They also get someone who understands the Claudia of it all, albeit in different ways. The Claudia that Soren is nostalgic for is one that Terry knew only pieces of, and the Claudia that Terry misses is one who had already become Soren's nightmare. That said, they are united in remembering her with fondness and love ("I miss her too") and having someone they can share those feelings with in a less complicated way than say, with Corvus — who never really knew her — or Ezran — who ignores and represses and has 'more important things' going on — that they're in immediate close proximity too.
At the same time, Claudia is a wound that can be very raw. If Soren doesn't want to talk about her, and he might not ("if you won't stop, then I will stop you" / "I don't want to talk to [/about] my mom"), that makes Terry's active presence a perpetual reminder of Claudia's absence. Terry is also a big feelings guy to his core; he will, at the very least, attempt to approach Soren about it, likely more than once, and his feelings will come out in other ways even (or especially) if he can't vocalize them to someone who understands. If Soren mandates that Claudia cannot be saved and Terry still insists that she can, that could also cause Terry to break things off in frustration. (There is also, of course, the possibility that Terry won't want to discuss Claudia, which could tear at Soren in a different matter entirely, that the one person he thought might understand doesn't want to at all and acting so counter to who he believes Terry to be / who Terry normally is, but I digress).
I also wonder if Soren might scaffold all of his grief about Claudia onto Terry, a la "Claudia doesn't want to talk to our mom" as a guise for "I don't want to talk to our mom". This could loop back around into moments or months of resentment (how dare you openly express that you miss her when I cannot or will not? how dare you not express it enough for me to vicariously live through you? nevermind that every time i goad you into opening up about it i turn around and get mad at you) given the way Soren behaved when he was a younger, less mature man with Callum but with significantly less grief.
Viren is also another sore spot. Terry loved and misses the man he knew, who is a decidedly different man than Soren knew. Does Soren find reassurance and comfort in the fact that Terry's memories of Viren affirm he was a changed man by the end, or does that just make Soren's grief over losing the relationship he never but could've had, finally, worse? Does Terry sit there, disquieted and mildly to majorly disturbed, as he learns Viren's actions through Soren's eyes in full, and isn't sure whether to prioritize the man he knew or the one Soren did? Is it wrong to mourn Viren when no one else is? Is it right to mourn Viren? (And again, possibilities for grief projection from Soren.)
And then, amid or despite all that, I think they'd get on famously even with their wildly different dispositions and hobbies. Terry will likely never be a crownguard, but Soren could still teach him how to defend himself; Terry would wholeheartedly enjoy Soren's poetic ventures. They'd laugh and have fun, sit around campfires and wait for Corvus to get back, Soren slowly unfurling memories of the kind king they're searching for, Terry eventually sharing a bit of how he grew up, too. I always knew who I was. Who I wanted to be. Who can understand the power of refusing to change who you are — and thereby changing also almost everything about yourself — to be your fully actualized self better than Soren?
Of seeing each other clearly, after — perhaps — constantly seeing each other obscured