Serena/Relationship

Yuzu Hiragi
Serena initially paid Yuzu no heed despite their similar appearances(though she was a bit shocked at first). However, when Yuzu told her the truth about Academia's cruel and immoral actions against the entire Xyz Dimension, she began to gain worries about her words and cooperated with her to find the truth from Shun. When she learned Yuzu was missing after the invasion, she was filled with great grief since it was because of her the invasion started. Due to this, she was adamant about finding Yuzu along with Yuya while in the Synchro Dimension.

Yuya Sakaki
When she saw how devastated Yuya was when he lost Yuzu, Serena was filled with great remorse since the entire incident was partially her fault. When she returned Yuzu's cloths to Yuya, she promised to help him save her no matter what. However, her pride and arrogance got the better of her while facing the security in the Synchro Dimension causing her to put her allies in more danger when she broke her promise to Yuya by ignoring his escape plan.