"Yuusha" Party ni Sennyuu shita Maou-gun no Assassin ~Kiken-do SSS Class no Mission, Barenai You ni Ganbattetara Onna Yuusha ni Kiniirareta~ - Ch. 1.2

[MangaDex]

 

[Shrimperor]

Hmm
Interesting start. I am in.

Will our Heroine be corrupted, or the spy be redeemed?

 

[EggMiner]

Hmm
Interesting start. I am in.

Will our Heroine be corrupted, or the spy be redeemed?

It's always the spy betraying them, realising that the rewards he receives aren't worth it, returning and then guiltily begging for a chance to redeem himself till the climax where he jumps in front of a killing-blow and they forgive him.
The only time the heroine is corrupted is in H/ecchi manga.
What I want to see here is him betraying them and then them doing everything to take revenge. But, I know it's more likely that the former is most likely the case here as well.