How can you like Katrina after she had a hand in killing her mom and also not warning Galen Cox about the attempt on his life?
There were others like her before, and strangely those are amongst the popular and beloved rulers of the fanbase.
[spoiler]How can people like Hanse Davion after he has killed tens of thousends soldiers in the fourth succession war just because Maximilian Liao dared to scratch his ego?
He planned a scheme that killed his own brother in law, and sent one of the most popular and famous units of his House to die, because they prefered Michael Hasek-Davion over him.
He even told his own generals that they can either serve him or be sent to die like the 5th Syrtis Fusiliers. (the unit mentioned above)
Also, the Project Gemini was Hanses idea, he just never had to use it because Joshua was still healthy (as healthy as you can be with a fatal disease at least...) while Hanse was alive.[/spoiler]
Katrina is really just Hanse 2.0, combining the wrath and intelligence of the fox with the charm and political wits of Melissa.
Out of all all Steiner-Davion children she is the one who fits most with the pre-clan-invasion cast of the BT universe.
Arthur is a plain old racist and to occupied idolizing James Sandoval to do anything worthwile.
(Exept dieing in a fire... (almost) litterally)Yvonne is pretty much useless. She might be intelligent and charming, but she is waaaay to soft to be anything more then a hindrance.
Victor is way to retarded for his own good, he has absolutely zero political skill and his only means of survival is relaying on his much more competent friends. (tough he gets the credits for anything they do...)
Peter is so-so, he is my second favorite Steiner-Davion child. He might be a sissy and spoiled brat before the exile, but the Peter that appears after that is a pretty good commander and leader.
and surprisingly I like Focht as a character especially later on (again twilight of the clans series and onwards).
I always found it funny who Focht really is...

[spoiler]One of the most scheming Steiners turns out to become the great hero of the IS and is generally seen as one of the greatest heros ever... Frederic Steiner.[/spoiler]