A few mage or mystic friends to keep the dragon alive, just as players already do with certain peerless bosses that have area effects. One type of captain, I forget which, has a really, really large area effect. Most are smaller, so a spellcaster can be outside the damage area but close enough to heal the dragon.
My complaints are with other things. I don't mind that a captain generally requires teamwork, which is a refreshing change from a single char being able to solo most anything. I did solo a captain tonight with a warrior, not a sampire, just chivalry and no bushido. I stood toe-to-toe for most of 20 minutes, not needing to joust. Every so often I'd have to back up and heal, but my hp/mana regen suit and Vampiric Essence cutlass (100% life leech and Blood Drinker) mostly kept my health up.