My neice is 3.5 almost exactly the same age as my ds1. I often see her, her sister, my brother and sometimes sil on a saturday at my parents.
Anyway my neice is an inteligent, talkative little girl who plays lovely with my ds1. However I have also found quite a few times lately that she will make out that she is holding my ds2s hand aged 17 months when she will suddenly start to pinch him hard or twist his wrist or a kiss will become a bite or a cuddle a strangle etc. She has a sister that is 3 days older than ds2 that she is similar with. This I can sort of understand because of jealousy reasons but why my ds2? She is normally a delightful child!
Also if I tell her off for this she ignores me completely and I have often had to literally yank ds2s hand away from her which sometimes makes things worse as she often continues to hold on. She will only listen to her daddy who isn't always in the same room for instance may be talking to my dad in another room etc.
Have had unpleasant incidences between ds1 and 2 but always when ds1 is unhappy/tantruming or tired etc not when he is other wise happy iyswim. Unsure how to deal with tbh!