You might have missed this Brett detail on the Chicago Fire finale

One Chicago has given fans lots of marriages over the years. Recently, it's been used as a means of signifying that the characters are moving on from the show. Chicago Med said goodbye to Dr. Ethan Choi (Brian Tee) and April Sexton (Yaya DaCosta) by marrying them off, and Chicago Fire did the same with Matt Casey (Jesse Spencer) and Sylvie Brett (Kara Killmer).

It's rare that we get insightful bits of information about their lives once they leave. Chicago Med hasn't really made reference to Choi or Sexton since they left, and Chicago Fire seemed to be doing the same with their beloved couple. Until we got to the season 12 finale, that is.

Sylvie Brett has taken Casey's last name

Sylvie Brett didn't appear onscreen, but she sent Stella Kidd (Miranda Rae Mayo) a text message that sparked a huge moment in the episode. We've already discussed the bombshell chat that Kidd had with her husband, Kelly Severide (Taylor Kinney), but the detail that may have been lost in the mix of baby talk was the way Brett was saved on Kidd's phone.

Instead of having the character's name listed as Brett or Sylvie, the number on the phone was under the contact "SC." This confirms that Brett is no longer Brett, but has taken on the last name of her husband. She's now Sylvie Casey, which feels as strange to type as it does to read.

Most Chicago Fire spouses keep their surname

This is actually a pretty unique development within the One Chicago franchise. In the past, female characters who have gotten married have decided to keep their own last names. Hailey Upton (Tracy Spiridakos) was still Upton after she married Jay Halstead (Jesse Lee Soffer), and even Stella Kidd kept her surname after tying the knot with Severide.

Brett's decision may be a reflection of where she lives, and the type of domestic life that she's trying to fall into. She's built a very picturesque life with Casey, her adopted daughter, and the two Darden boys in Oregon. On a more practical reason, Brett is no longer on the show, and so it's much easier to alter her name when she's not being referred to constantly in the field.

It would admittedly be confusing to hear the name "Severide" shouted out while Firehouse 51 is trying to save people from a fire, only to realize that the person saying it is actually referring to Mrs. Severide, aka Stella Kidd. A small detail, but an impactful one.