Miracle hates drummers because she dated one.You know how her catchphrase "Drummers are creeps?" It's not just a non-sequitur. She dated a guy who was a drummer in a band (Merch's biological father) who was a creep and a jerk.
Stuart is a fusion of both Larry and Miracle who's from the future and faking his insanity.His personality is more similar to Miracle's, but he's a fusion of Miracle and Larry's DNA. Even Andrew in canon says "It's (he's) like a combination of Larry and Miracle!" He traveled back in time from the future after being created by a Mad Scientist. He saves the day via Heroic Sacrifice.
Ennis was probably married at one point but then got divorced.Most likely due to cheating. His womanizing and sleeping around is how he overcompensates for everything.