Neville held on to him just like Theo held on to him during the war, keeping him together when fear and anxiety and imposer syndrome threatened to make him fall apart. He couldn’t joke or smirk like Theo could, but he could give all the soothing hugs he required, he could make sure he was well fed and their room routinely cleaned. Neville did his best, and slowly Theo started to get better, and the more he did, the more they started to worry together about Hermione.