Hank McCoy AKA The Beast, was a member alongside Carol during her time as Ms. Marvel. The two shared a playful relationship and Hank's humor seemed to bring out Carol's fun side. Carol left the Avengers while under the thrall of the obsessive son of Immortus, Marcus.
When she returned to Earth, she fell victim to the mutant, Rogue. While recovering at the X-Mansion, the Beast and Carol's other former teammates from the Avengers paid her a visit. During this meeting, Carol vented her rage and feeling of betrayal towards the team for their failure to see through Marcus' schemes. She blamed them for taking her "pregnancy" as a joke and not seeing Marcus for the threat that he was.
Time, however, heals all wounds, and when Carol arrived with other former members to deal with Morgan le Fay, it was the Beast whose company she sought. Both Carol and Hank have close ties to the X-Men, as well as the Avengers, and have had some contact over the years. When Carol's powers began to fluctuate, it was Hank that she turned to for help in figuring out what was going on. Hank reluctantly agreed to keep Carol's diminished power levels a secret from the rest of the Avengers.