Point of Clarification: FRCP 18, 19, 20, and 24 are all about one civil action--what parties and claims are joined in that one civil action. FRCP 42 involves multiple civil actions that remain separate civil actions, especially for finality; it simply allows some parts of those separate civil actions to be litigated together.
Puzzle to work on in your own time: VOA sues BSO on the breach of contract claim in state court; court issues final judgment. VOA then then sues BSO for copyright infringement in federal court. Is the second action precluded? Consider the "could have been brought" requirement.
We move to Responding to a Pleading: Motions. For Friday, prep all assigned rules except 12(c), 12(e), 15, 16, and 41. Read PAE; wait on Trump and Doe. Read Glannon pp. 401-17. Prep the motion in Naruto. Prep Questions 1-14.