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I don't think there is a particular word because the actor is the former slave owner. He or she is the one who freed Tsidia. So your descriptions would be about how Tsidia influenced the action...
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#3: Attribution notice added
Source: https://writers.stackexchange.com/a/40467 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
I don't think there is a particular word because the actor is the former slave owner. He or she is the one who freed Tsidia. So your descriptions would be about how Tsidia influenced the action, even if Tsidia is the subject of the sentence. "Tsidia convinced her owners to set her free." Or, as object, "The Jefferson family, moved by her oratory, emancipated Tsidia." Now, Tsidia is certainly the actor in her fate. To put her front and center where she belongs, you can name her actions. She is an abolitionist. An activist. The longer version being that she is a former slave, freed by her own persuasion.