I think he would be more straight forward than Solas. Pretty blunt as well...so similar in that way. Though I do agree he seems like he would have a dry and sarcastic sense of humor. Not a total ass but funny when appropriate.
I don't think he would have much patience for The Game. I think he would be similar to Cassandra in that way. He spent his life serving people that utilized their people like pawns for their own ends. He would likely understand its necessity but would avoid it at all costs.
If my Lavellan could date him. She totally would. She belongs to NO MAN. *snap*.
Yes,a mix between Cassandra and Sten is what comes to mind,to give a very basic,brief description of what I think his personality would be.
Although, no doubt the writers would add more uniqueness,as he'd be an entirely new character.
I can't see my Lavellan with Abelas,mainly because her romance with Solas had a meaningful impact on her and Abelas is probably the last person she'd date,after his remarks at the temple of Mythal.She respects him sure and is fascinated by the fact that ancient elves still exist but,she'd probably wouldn't go for it.I'd probably think the same about other Lavellans, who haven't romanced Solas or anyone else.
However,the idea of a new protagonist romancing him seems much better to me for some reason,if he'd be romanceable (because tbh,I do get an aromantic/asexual vibe from him).
This is just pure speculation though,in Leliana's words.