What if Carter went about this indirectly? For example, saying how he wishes Carter's body is alright and that it wouldn't die and something that only Carter would know such as "I can't believe you haven't changed your password for the last X years" or "I don't want to ruin yours and Alex's marriage" or even say bad things about Alex. He could give other clues to try to tell Aron indirectly, letting Aron put the two together.
If Aron asks, Carter would just say "I can't tell, it's against the rules"
Or is Mark watching Carter's every move and listening to his every thought regardless of distance and time?