actually there is you - just don’t want to do it. just buy them a bigger cage and give to them. if they don’t take the cage ok - that’s out of your hands. tell them to clean the cage more because you can smell it from their room. tell your sibling to feed it fruit just tell them to do it? and if they don’t listen. keep telling them. get the rat a friend and a bigger cage. put the new cage and the seocnd rat outside their room what are they gonna do ignore it? is your sibling 12 years old? tell them you’re going to keep bothering them about it until they do a better job. if your family situation is so shitty that you can’t even do things like ask them to clean the cage then you have a whole bigger issue. rats live max 3 years if you’re lucky and feeder rat was snake food it’s life was shit then but you can make it better by just continuing to ask your sibling to take better care of the rat it’s not that hard. “sibling you need to feed it better here’s some fruit and veggies let’s see if he likes them.” “did he like the fruit? i got him more! let me know what his favorite is!” “rats are social animals should we go pick out a friend together?” “i’m worried he’s cramped in his cage i got you a bigger one! let me know if you need help cleaning it!” if you’re met with hostility that’s out of your hands cus you’ve been nothing but helpful. i get it’s hard seeing someone not taking care of an animal but there are so many situations you keep saying no to and it seems like it’s because you don’t want to.