u/Inevitable-While-577

I will never forget the day I fetched you and your sisters from the shelter. You were just tiny babies. The assistant opened the enclosure and you darted out and escaped! What a struggle it was to catch you, and I thought oh well, she's going to be trouble! And yes, that's how you were. Incredibly good at avoiding being picked up. My beautiful, derpy, stubborn, clever little girl.

I thought a lot about a good name for you. You should have been called Stormy or something like that, but I tested a few names and you insisted on Aura. It was the only name you'd respond to the first time you heard it, and you would always, always react to it, so that was it. You would lick food off my hand so gently. You loved to collect and unwrap tiny packages I made, just small treats wrapped in a piece of brown paper. You were so smart and curious, but the one thing you wouldn't accept was being picked up.

In the beginning, I introduced you all to the three old rats I had at the time. Those months with the 6 of you were so magical and I'm glad you were with us. During that time, I very gradually managed to pick you up. Baby steps with lots of treats, no holding or cuddling but I could grab you if I didn't hold you for too long. I could place you in a carrier and have you accompany your chronically ill sister to the vet. This ended when they both passed, you regressed to not tolerating it at all. I think losing them really messed with you, my poor girl. I know you were happy, at least for a while. I wish it had lasted longer, I wish you didn't have to witness both your sisters (Milky Way and Nova) passing before you.

Your sisters and you were so different. I know you loved them immensely, and were grieving so bad when they passed one after another. They shouldn't have gone so soon. It’s not fair.

Even though you had new cagemates by then, it just wasn't the same. You got very sick a few weeks after Nova's passing, and though you were the healthiest of the bunch, you declined quickly. You were only about one year and three months old.

You were an absolute crackhead for malt paste. If I had let you, you would have easily eaten an entire tube at once. In your very last moments before I took you to be put to sleep, you weren't eating or drinking, not even yoghurt, but you did lick some malt paste from my finger just before we left, and I'm glad I could make your last day at least a little bit sweeter. Rest easy now, beloved Aura.

Unamused pancake for tax.

Had a bit of a "duh" moment today when putting a ceramic tile in the freezer for the rats (which admittedly I've been doing for the last days without a problem): terracotta/unglazed ceramic isn't frost proof. This is widely known for flower pots (shouldn't stay outside in regions with harsh winters), because the porose material can retain water, which may freeze and expand and crack the material.

I don't really think it will happen for putting tiles in the freezer for a few hours, but I wanted to mention it. Wouldn't want anyone to get injured. Just be cautious when taking them out of the freezer in case they've cracked, especially if you cleaned them with water right before freezing. (Or just put them in the fridge instead.)

TL;DR: tiles may crack while freezing - be careful handling them.

Please note: This is not about nibbling, biting from poor eyesight, thinking that hands are food. It's not only about biting when picked up. It's not about hormonal aggression. The rat has clearly aggressive body language and actively attacks/hunts me.

TL,DL: rat too old to unlearn aggressive behaviour - need a way to get her to relax, at least enough to not actively attack. Most important parts of post are bold.

Long story short, I recently adopted 2 new rats from a shelter with the intent of introducing them to my 2 girls (because sadly after several deaths, I had only 2 left). They're currently in a quarantine cage in a separate room.

They're female, 1.5 years old. Haven't been handled much and afaik always lived as a pair. They don't know how to lick yoghurt from a spoon or finger, they seem unfamiliar with a lot of things. I let them free roam daily in the room, and they seem to enjoy it.

One of them is very shy, easily startled, can't be picked up, typical rescue rat behaviour. (She'll sometimes bite my hands softly in the typical "is this food or body part" way, which is fine, I know how to deal with that. I've had several like her before.)

The other one however is seriously aggressive in a way I've never experienced. She's not shy. She'll rush out of the cage as soon as I open it. She climbs on me since day 1, uses my body as a bridge. She acts confident but her fur puffs up as soon as she touches my body. She takes treats from my hands but her fur puffs up. She has even side walked (crab walked) me just sitting on the floor and handing her a treat. She chases and attacks my feet when I walk so I need to wear shoes. She hates being picked up, but she lets it happen more than her sister does (doesn't run away). Once she bit my finger and drew blood.

She'll climb up my leg or arm (with puffed up fur!) and all the way up to my shoulder. Once, she was on my arm, I was facing her and talking to her, she was completely still then suddenly darted to attack the collar of my hoodie. I'm lucky she didn't bite a few centimetres above, on my bare neck. I am now scared of her and don't want to let her on my shoulder or near my face.

My concern is that since she's pretty old, it's probably learned behaviour, not hormonal, so spaying wouldn't help and it's possibly too late for her to unlearn. I have no idea how they were treated but it must have done a lot of damage.

I haven't started introductions. I fear that since they've never lived in a group, she might turn out equally aggressive towards my rats, but I don't know that yet. If I'm lucky, her behaviour is only towards humans. I've had many rescues and I don't need them to be cuddly with me or very easy to handle. I'm fine as long as they all get along. But in her case, I want to at least stop her from actively attacking me.

So here's my actual question: how do I teach her not to actively attack me? I feel there must be two approaches: either try to "dominate" her, basically force her into relaxing with me, kind of like a dominant rat would do (force grooming, etc.); or the contrary, showing her that she won and I'm "submitting", though I have no idea how one would translate the latter into rat language. The former seems more feasable but will this really serve to calm her down or would it just traumatise her more?

She's an extreme case because she's fairly old. I feel at this point, the gentle method (treats, sitting with her calmy, letting her climb on me) will NOT work. And I can't limit interaction either (as one would with a skittish rat) since she actively approaches me.

If anyone has had a similar case, I would really appreciate some insight.