berault said:
The Man (Viggo Mortinson's character in "The Road")
This guy is jam-packed full of survival instinct and will-power.
That being said, any fictional character played by Viggo Mortinson would be a good companion.
See Hidalgo or Eastern Promises if you need proof of that statement
I can't be the only person who thought he was in his mid-thirties after seeing him play Aragorn, can I? Seriously, I was really surprised when I found out he was in his fifties at the time that was filmed...
Anyhow, I'd probably pick Seras Victoria, Lucy (Elfen Lied), or any of the girls from Higurashi No Naku Koro Ni, as my companion on an adventure. Reason being, an attractive girl is always useful on an adventure, if only for helping to get into places, and it helps to have people who know what they're doing in a fight, too

. Especially useful if the crazy psycho girls are on
your side, not the enemy's...
Mortenson is in his 50's! WTF?
Failing that, Samwise Gamgee, just because I've always wanted my own personal
***** manservant.