Bias is a thing, which is why I commented that my positive outlook about Severes should be scrutinized against my love for my Jericho, just as the negative comments from a Hahn's breeder should also be suspect (i.e. they want you to buy a Hahn's). I also have a sample size of one (Jericho).
If you search this forum for "Jericho" posts by me I've written about his background and my experience numerous times (most recently when he broke the foot of my little Marvin). He was an only bird for over 10 years before he came to me, and his previous caregivers gave him up because Jericho chased their grandkids. As you've commented, "birds have their own personalities", so it's difficult to know how much of this is nature or nurture. My theory is that, being an only bird for so long, Jericho learned to bond too strongly with his humans. That bond has transfered to me (in isolation, he's the "perfect" bird... with me), and we've been working on lessening it. Jericho has chased my other birds, and visitors, so it's in everyone's best interests to shift this bond to something healthier. It's a slow change to unravel.
All that said, over-attachment is not a problem that's exclusive to Severes.
At the heart of many behavior problems is a social relationship that has taken a wrong turn. Why? Because, despite our best intentions we often misunderstand what parrots really need from us social…
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Whatever species you end up choosing, it's best to avoid establishing a pair bond.
Serveres are large enough that these behaviours can be dangerous.
The very same actions from a Hahn's would be less so, and from a Military (my Oscar) they'd be even worse.
I'm happy to answer any questions.
Regarding this...
You
will encounter difficult situations when living with any species, so get as much experience as you can, and use forums like AA to lean on others when the going gets tough.