Situation we got on our last game:
Death walks among us winter card was drawn. It says: "Perform an influence bid. The lowest bidder must choose one hero to desert him unless he discards 5 influence or 5 tactics cards".
We performed the bid, and i was the lower bidder, but i had the title card "Captain of the heroes league", that says my heroes never desert, so if i don't discard the influence or tactics cards, i remain unaffected, right?
Correct. Heroes never desert you if you have that Title, for ANY reason (unless you want them to). So if you are the lowest bidder, you could choose not to discard anything and the hero will still not desert. It's similar to the new Merchant's Guild title that says you cannot lose resources from season cards; you can use Gifts for the Rich without spending any resources!
(Just as a note, though, the Coercion tactics card does NOT count as desertion; having the Captain of the Heroes' League card will not protect you against Coercion).