Complex sentence: After she loses a Rock-Paper-Scissors game to Sora, she is ordered by Sora to "fall in love" with him as a punishment, forcing her to become the siblings' underling with no choice but to comply with their demands.
Split into simpler sentences: After she loses a Rock-Paper-Scissors game to Sora, she is ordered by Sora to "fall in love" with him as a punishment. Thus, she is forced to become the siblings' underling, with no choice but to comply with their demands.