In Summer's younger days, she enrolled to Beacon Academy and became a member and leader of Team STRQ, along with Taiyang Xiao Long, Raven Branwen, and Qrow Branwen. She and the team eventually graduated to become Huntsmen and Huntresses.
At some point later in life, Summer entered a relationship with Taiyang after Raven left, the two had their daughter, Ruby Rose, and Summer took to raising Raven's daughter, Yang Xiao Long, as well. Summer's family lived in Patch as she left regularly to carry out missions. According to Yang, Summer was like a "supermom", "baker of cookies" at home and "slayer of giant monsters" due to her Huntress career.
It is revealed by Qrow that Summer acknowledged and utilized her abilities through her silver eyes. It is unknown when and how she discovered her abilities and to what extent.
When Yang and Ruby were still young, Summer went on a mission and never came back. Specific details surrounding her fate are undisclosed or unknown. According to Yang, Ruby was too young to likely be able to fully comprehend what had happened.
Taiyang did not handle the news nearly as well; Yang says he simply "shut down". It is after this that Yang learned Summer was the second love that he had lost, the first being Yang's mother, which makes Summer Yang's stepmother.
In "The More the Merrier" Ruby attempts to sway Raven into joining the fight against Salem. Raven responds, somewhat contemptuously, "You sound just like your mother", before beginning the attack on Haven.