How would I write a query like this using Exposed?

SELECT requested.GroupId, requested.Member, requested.isAdmin, requested.isOwner
  FROM GroupMembers requested, GroupMembers requestor
  WHERE requested.GroupId = 1 AND requested.Member = 1 AND requestor.GroupId = 1 AND requestor.Member = 2

Use aliases https://github.com/JetBrains/Exposed/wiki/DSL#alias

Ah excellent thank you!