Does iMessage read your messages?
No — iMessage cannot read your message contents, because chats are end-to-end encrypted by default; only you and the recipient hold the keys. What it can still see is metadata: None by design — Apple's IDS and APNs servers see sender/recipient identifiers, timestamps and routing data in cleartext; only message content and attachment bodies are E2EE.
Even when contents are encrypted, the service usually still sees who you talk to and when. iMessage's identifier model: Apple Account (Apple ID) bound to a phone number and/or verified email address, registered with Apple's Identity Service (IDS). RVNT removes the server from the equation entirely — peer-to-peer, sealed sender, Tor by default: RVNT vs iMessage.