I'll probably add to this if I come up with more ideas, but this is what I currently have:
Questions at the Summoning:
“Who is in charge of the Seekers?”
“How do you justify the lack of oversight?”
“If you were aware of the disappearances among the Seekers, why did you continue sending them after me? Did you just cross your fingers and hope that one of them would manage to find and drag me back to Olympus before they became the next missing persons case?" Express disapproval at the gods’ callousness.
Regarding the Seekers’ unsuccessful attempts to find MC: “If getting me to Olympus was so important, why didn’t you look for me yourselves?” Admonish the gods for their arrogance, if that was what kept them from doing something as ‘menial’ as a retrieval mission. (This is assuming the gods didn’t look for MC themselves)
“Do you have any idea what the cause of their strange behaviour might be?” Hint at possession if that was MC’s original hypothesis
“Now that you know the Seekers are acting up, what do you plan to do about it?”
I feel the MC should be going over the basics of the Trials with the gods, not the Scooby gang, since the gods are the ones who insist on MC’s participation. Though I suppose being forced to get information from the Scoobies could contribute to the whole Underdog!MC vibe (because heaven forbid anyone tells MC anything). But if you do go this route…
“What are the Trials exactly?” / “What do they consist of?”
“How long will it take to complete the Trials?” (days/weeks/months)
“Who’s participating in the Trials?” with the following a potential response: “So you’re ok with potentially sending your kid to their death”—>can be either a statement or a question Cue contemptuous smile or incredulous look
“What’s the prize for winning?”
“How much time do I have to prepare?”
“Why did you (Hades) leave?” based on whether Hades tells MC of the Council’s interference during MC’s initial reaction to seeing him
Directed at the Council: “Why did you keep Hades from seeing me?”
“I’ve noticed Athena isn’t here. Where is she and why isn’t she here?” Alternatively, MCs could figure out Athena’s identity, based on Saint and Calypso’s reaction when MC brings up Alice, the revelation concerning Hades/Henry’s true identity (if Hades helped raise me, could other gods be involved in my upbringing as well?) and by drawing parallels between Alice/Athena’s absence and personality (according to the description Saint gave of her during the Q&A in Athens and MC’s own knowledge of Alice’s personality). MC could ask why Athena raised them and express rage when they learn of the reason for Athena’s absence, because how dare you take away my family (and subject her to Tartarus)! and/or no thanks to you, I’ve spent the past three years wasting away on the streets.
“Will I live at the Institute?” / “Do I have to live at the Institute?” For those who headcanon their Bearer already having a stable(ish) home they don’t want to leave or just not wanting to live on Olympus
“Do I have to attend classes?” For the Bearers who want to attend school in the mortal world, don’t want to attend school in general, or wish to avoid being on Olympus as much as possible.
“You mentioned two people earlier; the Bearer and the Bestower. Who is the Bestower? Are they on Olympus? When will I meet them?”
In response to the gods' distrust:
My MC doesn’t care that the gods distrust him. In his opinion, they are free to feel however they wish about him because
a) they’re unfamiliar with him and they don’t have any real reason to trust him
b) their wariness is understandable; if he was in their position, he would be equally suspicious, because who in their right mind would trust a hormonal seventeen year old with anxiety with the power to obliterate the entire universe?
c) he doesn’t exactly trust them either
However, that doesn’t mean he’s happy about being insulted and threatened by Ares and Hera. So the option to calmly trade barbs with the two of them and to tell Ares to back off when he threatens Hades, would be great. He would have ignored Aphrodite, Hestia, and Hephaestus.
Bargaining for MC's assistance:
My MC would ask to be left to his own devices whenever he wasn’t attending classes or participating in a trial. This includes being given the freedom to wander the mortal world and Olympus as he pleased--without a chaperone. Whether this request is accepted or denied could be influenced by the God’s trust bar.
He would also like a promise that the gods will not interfere with his life nor attempt to drag him into their problems post-war. Whether or not the gods keep their word is another issue I won’t get into.
Talking with Father-dearest:
How did he feel when he learned Athena kidnapped MC?
(Father= Hades/Poseidon) What was his reaction to Athena’s sentencing (and the impact on MC it implied)? (Father= Zeus) Why did he sentence Athena to Tartarus? (Father= Poseidon) Did he agree with the decision?
(Father= Zeus/Poseidon) How much does he know about MC’s life with Athena? His opinion on Hades’ involvement in MC's upbringing.
(Father= Hades) Why did he help Athena raise MC? What happened to him after he left? Does Persephone know he is MC's father?
How much does he know about MC’s life on the run?
What does he think of MC’s chances of winning the Trials?
How did they meet?
How long had they known each other?
What was their relationship like?
What was she like? Does she and MC share any characteristics? (personality check)
What happened to her?