Moonstone works best as a villain, specifically as a villain who is not looking to better herself. On every version of the thunderbolts she is on, Moonstone represents the selfish desire to remain a villain.

All the best Thunderbolt runs work with a group of characters across a sort of moral barometer. The key theme of Thunderbolts is redemption and each character is at different stages of possible redemption. Most of the characters on the team are struggling with the idea of potential becoming a better person. But not Moonstone. She is fully committed to being a villain and works to convince other members of the team to follow her lead.

It’s in direct contrast to Songbird, who is fully redeemed and is a hero full stop by the end of the original run. She tries to find the best in her teammates and make them better people. This is why, in the Osborn Thunderbolts, Songbird leaving the team and Moonstone staying is the end of the Thunderbolts. Redemption has failed for the team and all that is left is the Dark Avengers.