I feel like Elrohir would be a catalyst. He, like Nwalme, has a heavy role in the goals and achievements of others. I feel as if Elrohir was the kind of person to take pride in doing exactly that. While he has taken on projects of his own, roughly two thirds of them go flop (Most of these were due to lore that one person put on the wiki as canon. However, it was later revealed to in fact not be canon, and was put there without the permission of the lore team in general and thus Elrohir's project was scrapped. )
I feel as if Elrohir is a character that the protagonists would talk about, but very rarely actually encounter. The only moments I can think in which they would encounter Elrohir is through various Darkblood activities and the whole deal with the fall of the Inquisition, which I feel would be a large moment in the general plot of things.
I can never really decide with Ulfberht and Light. I feel as though Ulfberht would be a regular appearance, but hold no importance, whereas Light would appear once, twice at most (so far) and play a somewhat significant role.
-K9