Accidental Baby Acquisition is a trope found in a number of both canon and fanworks. In laymans terms, the pairing of the work accidentally acquire a baby and have to take care of the kid together. This trope is usually used to bring together a pairing through the joint care of the baby or child that they have found themselves in possession of, although sometimes, the story is more focused on the situation that resulted in them winding up with a child. While the child is usually found by one or both of the pairing involved, sometimes the child is given to them to tend by a friend or family member; in some cases, the baby is a friend or teammate who has been de-aged. Depending on the situation, accidental baby acquisition can be long-term or short-term. Long-term fanworks usually involve an orphaned child that the pairing adopts.
Example Canon Works
Bones, S03E12 'The Baby in the Bough'
Castle, S06E10 'The Good, the Bad & the Baby'
'Life as We Know It'
Sherlock Holmes ('54 TV series), E26 'The Case of the Baker Street Nursemaids'
'merry and bright' by BerryliciousCheerio. Agents of Shield, Jemma Simmons/Skye|Daisy Johnson. Is there a better Christmas gift than a literal baby? or: how the johnson-simmons family came to be
'Thrown in the Deep End of the Parenting Pool' by crystalkei. The 100, Bellamy Blake/Clarke Griffin. Octavia leaves Bellamy with her brand new baby while she goes out to find Lincoln. Clarke helps and their relationship finally progresses.
'Everyone Loves The Kitsune' by rvst. Teen Wolf, Malia Tate/Kira Yukimura. Kira loved that about her girlfriend. Even if it ended with them babysitting for their friends more often than not, Kira still loved Malia's natural affinity with children. They hated Kira herself.
Which made her current situation all the more strange.
'it takes a village' by theyoungestzerogmechanic. The 100, Clarke Griffin/Raven Reyes. Clarke and Raven find a baby in the woods and the rest of the hundred are more excited than they should be.
vignettes of domesticity by aghamora. How to Get Away With Murder, Laurel Castillo/Frank Delfino. “All he has in his fridge is leftover Chinese takeout and beer. Laurel sighs. She’s never seen anyone less equipped for parenthood than Frank Delfino.”
Or, Frank suddenly finds himself responsible for a baby. Laurel is there to help.
'Accidental Baby Acquisition' tag on AO3