Garrus and Thane, Dragon Effect didn’t ref any particular DA characters for these two.
The storyline I’m thinking for Garrus is that turians are a regularly integrated part of society and as with Mass Effect where they make up the bulk of C-sec they often fulfill the role of town guards and in Garrus’ case he’s risen to become a captain of a wealthy trading town, hence his somewhat ostentatious get-up. He’d be a melee/ranged fighter.
For Thane I’d see him as belonging to a small almost forgotten order with the purpose of finding and eliminating wild dragons or wyrms. That’s why he’s wearing a light dragon scale outfit and the glowing stone set into his chestpiece is a gem that embues him with added marksmanship powers.
Next up was going to be Tali/Liara but I really want to do Mordin so I think I’m gonna give him a shot, not sure who will be paired with him yet, might just have it be Tali anyway since I’m sure she’d be a popular choice . I’ll pair Liara with Javik when I get around to it.