Most recent quests forgot about the option of adding Reputation (fame),
See some of those in TR that do give rep.
Reputation can be increased as a result of certain high-profile events, heroic deeds, or even if the player rescues people (non-controversial, not slaves) who’ll spread the word, etc.

Please also point out any current quests that could reward the player with e.g. “Infamy”?
TR hasn’t added any such global variables yet. One should be TR_CapturedSlavesCounter (opposite of vanilla FreedSlavesCounter)