Elias, through a Leitner or artefact or otherwise puts Martin in an extremely horny and unable-to-fight-back state before setting him up as an amenity for one of his charity galas. The donors are all welcome to use him and they use him thoroughly. Some just fuck him, some play with the plethora of toys and other implements Elias set out, some do both. Peter and/or Simon could take a particular amount of interest in him. Afterwards, Martin is left fucked-out and dripping open. Elias might take him home, then, use him himself before cleaning him up and setting him to bed.

Trans Martin isn't required but it's very welcome. Also welcome is some fucked up victim blaming— Martin might obviously feel horrified after but is unaware that he was under the influence of an artifact and so thinks he wanted it.