Subhadra
Subhadra was daughter of Vasudev (father of Shri Krishna) and she was sibling of Balram and Krishna. She was extremely beautiful, had large eyes and very pleasant to look at, she was also very modest and humble as she presented herself as milkmaid to Draupadi and Kunti when Arjuna asked her so because Draupadi was unhappy that Arjuna brought Subhadra to Indraprastha.
The story of Balram wanting to marry Subhadra to Duryodhana is not in original Mahabharata but it's mentioned in Srimad Bhagavad Mahapurana. When Arjun was in penance exile, he heard that Balram wished to marry off Subhadra to Duryodhana and except Balram, none of the family members wanted it. So, he went to Dwarka and with the permission of Vasudev, Devaki and Shri Krishna, he abducted Subhdra which greatly angered Balram but after being pacified he accepted marriage of Arjuna and Subhadra.
Duryodhana and Subhadra had no interaction in Mahabharata before or after her marriage with Arjuna.
Source- Shrimad Bhagwat Mahapuran