Before Fabian received Yohana's letter, he had already learned about her return and recovery. However, it was still more pleasant to hear from his sister herself.
Even though he wanted to run to the palace and embrace his sister, he couldn't. He was aware of the possible negative implications of showing his brotherly love to Yohana, who was currently in the body of Lady Runa.
Despite Yohana's letter, Fabian still couldn't recklessly visit her too soon. It would create gossip if someone took it the wrong way. Therefore, Fabian was grateful that Henrie went out of his way to summon him.
Henrie claimed to summon Fabian to discuss the investigation regarding Yohana's kidnapping and Princess Eleanor's unlawful acts. But Fabian knew better that Henrie was providing a chance for him to check on Yohana.