one's own; belonging to oneself, As for [topic], what [they] themselves did, said, or wanted…
→ は
phraseExtremely common#271
one's own; belonging to oneselfUse 自分の before a noun to say that the noun belongs to the person being discussed or to the subject. The は marks the topic before it.
Tom ate not only his own dessert but Mary's as well.
phraseRare#23,949
As for [topic], what [they] themselves did, said, or wanted…は marks the topic, and 自分の refers back to that topic as the doer in the following modifying clause. The phrase introduces a noun or nominalized action.