I'll take a look later when I get home to double check, but I'm pretty sure I've had multiple friendlies get turns one right after the other and not you / them / you / etc.
I invite you to check these pics:
ALL of these initiative queues are arranged alternately.
The two last pics? When the fights were proceeding:
- the voidling in the swamp, which was last in the queue and behind prince, suddenly spiked up to #2 once all its buddies died.
- the zombie that is behind me in the witch cave fight suddenly started acting after beast once all the other trash died.
THE CONSPIRACY IS REAL