I would like to know why did he target them or that house?
Was he stalking all of them that lived there or just one?
What was the trigger to finally attack on Nov. 13th?
Was he spotted stalking and called out? Feared he was recognized? Confrontation and told to f*ck off? for example.
MOO
I have the same questions. Right now, I don't feel we know nearly enough to say if ANY one person was targeted in that house and LE has never confirmed that an individual was targeted.
So, my own mind focuses on Targeting the House. Also, general victimology.
I believe he started out choosing U of ID as his target for his crimes, because he knew from his classes that when a killer goes out of one jurisdiction into another, it complicates things for LE. However, he wasn't paying close attention because Pullman and Moscow police have all kinds of connections and often operate smoothly and jointly, due to the nature of their towns. He ought to have gone further away, but I think he's very unaccustomed to being on his own or traveling far on his own.
Why choose a college town? First, there are lots of sketchy situations that students get themselves into (walking out late at night, not locking doors, not being particularly concerned about nearby strangers who look like students, etc). Second, I think BK hated the easy sociality of the undergrad population at the relatively compact and self-contained campus of U of ID. His own student housing was a couple of miles from the main campus; 1122 King Road was centrally located for student social life. He had been excluded (IMO) from an active student social life in high school, then again at community college (which was a commuter college), and then of course, by the hybrid nature of DeSales university where he didn't even meet some of his professors.
Deep inside, his identity formation has been squashed by lack of proper socialization as a regular student, he knows it, sees it and regrets it. Then, when the students he's TAing rat him out to the professor, his hatred of students goes up another notch.
I also believe he hates humans in general (rather obviously).
This was a crime against aspiring young people, their families - and his own family. It was a crime against all the people of Idaho, who were anxious and grieving along with the families (and all the rest of us who care). It was a crime against the partying culture of people he perceived as "not serious" students, not like him. He saw himself as better than those students, but they were the ones who (from his POV) were privileged and acting entitled. Doesn't even matter if any of the women ever ran into him, we know that he had had less than ideal interactions with other women and appears never to have had a GF or SO.
It was a crime against LE and criminologists, as well (the hatred bubbled up after the prof took the students' side in the grading matter). He had been planning hate-based crimes of annihilation in his mind (practicing them might be a better word), likely for years. Maybe most of his life. He was rejected as an intern by Pullman PD, etc. It was a crime against his own professors, whom he has made into caricatures, basically.
<modsnip - treading the line speculating about family - please don’t>
He didn't need a specific victim. I believe he wanted to compete with Rader and Bundy and to confound criminologists and others who study crime with the peculiarity of his crime. Before he attacked, he thought he'd get away with it. He acted in a robotic manner during the crime, having practiced the physical parts of it back in his own apartment and mentally while boxing. He did manage to tie both Rader and Bundy for most victims at a single crime scene, if I'm not mistaken.
I would not be surprised (when he dumps his memoirs on the world) if BK actually had the number 4 in mind before he started out that night.
IMO.