Im a wood elf, who has not been able to keep out of trouble with the law, which has forced him into Skyrim.
Im mainly a sneak archer, who does a little bit of 1 handed when i get spotted (which is rarely now)
I just completed the Theives guild questline, which seems appropriate for my character.
I also am planning on doing the DB questline, but am saving that because i just did it on my jack of all trades character and i want it to feel fresh.
I was mainly wondering if anyone can see my type of character doing the Companions questline. Im divided on my opinion of whether or not my character would do it so Id like some opinions.

You could have him do it to become a you-know-what with the excuse of furthering himself.

Edit: possible spoilers

You should do the companions. It can be done very easily as a stealth based character. I just finished it yesterday in my Stealth-Archery let's play on max difficulty and it wasn't very difficult