Blac Chyna has been accused of "preying" on Rob Kardashian.
E! News reports sources close to Rob worry that Blac, who has been involved in a bitter feud with Rob's sister Kylie Jenner ever since the teenager started dating her ex-fiance Tyga, is using the reclusive reality TV star to get back at her nemesis.
The insider added that there is concern that Blac is "preying on Rob during a weak time".
While Rob has retreated from the limelight over the past year after his weight ballooned, the pair have stayed in touch, with the source explaining: "She and Rob have known each other for a while and she had been staying in touch."
Rob's relationship with the model was revealed after Blac posted a picture of herself in an embrace with a tattooed man, whose inkings match Rob.
And just hours later his sister Khloe Kardashian posted a cryptic tweet about family loyalty, which read: "You can do anything. But never go against the family."
Blac is also the mother of Tyga's son King Cairo and has been locked in a bitter public feud with Kylie ever since the teenager started dating her ex.
She also used to be best friends with Rob's sister Kim Kardashian West, 35, but they are no longer close.