Complex sentence: The female protagonist, Liénor, is notable because of her active nature--she herself unmasks the seneschal, and found a quick successor in the active female protagonist of Tibaut's "Roman de la Poire".
Split into simpler sentences: The female protagonist, Liénor, is notable because of her active nature: she herself unmasks the seneschal. She found a quick successor in the active female protagonist of Tibaut's "Roman de la Poire".