|Gallery of Cassie images (1)|
In Knight Vision, Barney and Robin offer Ted three girls to get together with at their wedding. Ted picks Cassie, who appears to be the poor choice. Cassie becomes despondent and dependent on Ted when she learns that she has lost her job, where she was hated by everyone, her ex-boyfriend is also a guest at the wedding and has hooked up with Sophia, and her parents unsympathetically leave Ted to comfort Cassie after he meets them. When their attempts to become intimate become increasingly unlikely, Cassie graciously allows Ted to leave her so he can still enjoy his weekend. However, everyone already believes that he and Cassie are a couple; when Grace finally arrives, Ted's last attempt to find another date is ruined when he proposes a toast in memory of Reverend Lowell, only to discover that he was Cassie's uncle. Ted excuses himself and says goodbye to Grace as he is forced to spend the rest of the night comforting Cassie.
Although they both start off well, Cassie finds out that she has been fired as a teacher and everyone hated her. She also tells Ted that she has just broken up with her boyfriend Wesley, and starts crying, with Ted having to comfort her. They both later have dinner with Cassie's parents, and Ted is left to pay the bill. Cassie later runs into Wesley at the wedding, who has gotten together with another girl Sophia. Although she drags Ted to have sex with him, she starts crying in the room and also appears to be sick. She then allows Ted to leave so he can enjoy her weekend. However everyone at the inn now believes Ted and Cassie are a couple. Just then Grace, one of the girls Barney and Robin present Ted to get together with, arrives at the inn. Ted buys her a drink and makes a toast to Reverend Robert Lowell, who had just died, who turns out to be Cassie's uncle. Cassie is devastated at finding out that her uncle is dead and starts crying in the middle of the bar. Ted regretfully says leaves Grace to comfort Cassie. Future Ted notes that although he only made poor decisions that night, had he gotten together with someone other than Cassie at the wedding, he would never had met The Mother, so he in fact chose wisely.
In The Lighthouse, when Curtis, the frontdesk clerk at The Farhampton Inn, wouldn't guide Ted to the local lighthouse as he is single, Lily advises that Ted settle for Cassie, which she later acknowledges was bad advice. Ted reluctantly asks her to go to the lighthouse, although they both have nothing in common. Cassie then trips downs the stairs and sprains her ankle and Ted has to carry her on his back to the top of the lighthouse. Ted then throws up from the top of the lighthouse. Atop the lighthouse Cassie doesn't acknowledge the beauty of it all. Ted later realizes that settling would have been a mistake and he was glad he didn't. A flashforward reveals that Ted took The Mother to the lighthouse two years later and proposes to her which she enthusiastically accepts.
- Mother: Unnamed Mother
- Father: Unnamed Father
- Uncle(s): Reverend Robert Lowell