Does a creature with persist come back if it had a +1/+1 counter on it when it died?

Persist reads: 'When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.' The key condition is no -1/-1 counters — it says nothing about +1/+1 counters blocking the return. So a +1/+1 counter alone does not prevent persist from triggering.

Wait — let's be precise. A +1/+1 counter on the creature does not prevent persist from triggering. Persist only checks whether the creature had a -1/-1 counter on it at the time it died (CR 702.79a). If it had no -1/-1 counters, persist triggers regardless of any +1/+1 counters present.

However, there is an important interaction: if the creature had both a +1/+1 counter and a -1/-1 counter simultaneously, state-based actions cause those counters to annihilate each other (CR 704.5q). So they cancel out before the creature dies, potentially leaving it with no -1/-1 counters — meaning persist would trigger in that case.

Concrete example: Your Murderous Redcap has a +1/+1 counter on it (from Undying or a pump effect) and no -1/-1 counters. It dies. Persist triggers because there were no -1/-1 counters on it when it died. It returns to the battlefield with a -1/-1 counter (which then cancels the +1/+1 counter via state-based actions, leaving it at its base stats).

So to directly answer: a +1/+1 counter alone does not stop persist. Only a -1/-1 counter on the creature at the moment of death prevents persist from triggering (CR 702.79a).