Kim Kardashian, Rob Kardashian exchange rare tweets

Kim Kardashian and brother Rob Kardashian had a rare Twitter conversation Tuesday.

The 34-year-old reality star exchanged friendly tweets with her 28-year-old sibling after she complained of morning sickness on the social media site. Kim Kardashian and husband Kanye West are currently expecting their second child.

The conversation comes three months after Rob Kardashian compared his sister to Gone Girl villain Amy Dunne (Rosamund Pike) on Twitter. The reality star shared and deleted a photo of the character covered in blood, writing, "This is my sister kim, the bitch from Gone Girl."

Rob Kardashian largely keeps out of the spotlight, but was photographed outside an In-N-Out Burger last week. The reality star has struggled with his weight and depression in recent years, but mother Kris Jenner denied her son was in rehab in late May.

The siblings and their family star on E! reality series Keeping Up with the Kardashians, which will return from mid-season break in the fall. Kim Kardashian, sister Khloe Kardashian and half-sister Kendall Jenner are among those who celebrated Caitlyn Jenner on Father's Day.