My year was a bit different in that BP hired directly from the pool of intern candidates. My interview was in March, as the normal fall recruiting hadn't covered the needed number of summer interns. They emailed out in January saying that they would be doing an additional round of interviews, so I responded to express my interest. In the next few weeks, they sent out an invitation to come to Houston to do a site visit and interviews. I drove, but I know some people were flown in from out of state for the site interview Mon/Tues. I'd assume that the recruiting team was more or less watching the dynamics of the group, who got along with others, what group seemed to be the most interactive, etc. Of the people in the interview process, I got to know a lot of the more outgoing and personable candidates, and I think most of us got hired (if that says something about personality that they look for.) The actual interview consisted of two separate interviews. The first was technical, the second more of a softskill, tell us about yourself type. The soft skills interview was pretty typical, tell us about yourself. I think anyone can pass any company's behavioral interview if they can interact well and know the principles of the company (ie, read the mission statement and core values!)