When Tony goes to MIT, it’s the first time in his memory he hasn’t had his sweet little brother’s constant affection.
Tony gets really touch-starved.
During the holidays, Tony is clinging to Peter at every opportunity.
Always cuddling, walking with an arm around Peter, linking arms, pressing his leg to peter’s during family dinners, napping with his head in Peter’s lap when Peter’s doing homework. Tony even tried to sleep on Peter’s floor to be close to him before Peter dragged him to the bed.
Peter thinks it’ll wear off after Tony gets used to MIT. He soon realizes that he’s wrong. Peter accepts the offer to skip, Midtown have been sending for years. By, the next semester Peter is enrolled at MIT, but Tony’s as clingy as ever.
There’s the whole dramatic thing where they confess the loved each other all along, but they’re taking it slow for now. But no one notices any difference between couple them, and how they are usually because they’re so affectionate.
Peter starts noticing that Tony has developed some quite child-like tendencies and coping mechanisms sometimes, he also notices how much he enjoys taking care of Tony.
Peter researches this for weeks, and puts together a folder filled with documents, website links, and a PowerPoint filled with pictures/links of stuff he wants to get little Tony.
Peter doesn’t get around to broaching the subject to Tony. Tony finds the folder labelled Private, (because Peter didn’t think that through), and assumes it’s porn or a diary.
Tony read everything. He blushes while looking through the PowerPoint of stuff Peter wants to get Tony, slowly realizing how much he wants this. He want Peter to be his Caregiver, he wants to be taken care of, he wants to be his brother’s baby as well as his boyfriend.
When Peter gets home, Tony and him have a long talk about headspaces, regression and boundaries.
Afterwards, they curl up in bed together looking through different online stores to buy stuff for when Tony is Little