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A Wild Card is about unpredictability and chaos, while a Lovable Rogue is about charm and audience appeal, even if they're not entirely "good". A Lovable Rogue can be loyal to their team while still being a thief; a Wild Card might betray anyone at any time based on their shifting priorities.
A wild card will actively turn on you because they see an opportunity or the mood hits them. A Fair-Weather Friend just bails when things become inconvenient for them.

They both seem hard to distinguish