"He arrives in town to advise on Justin's case – which Tori is involved with both professionally and personally," Ditch tells TV WEEK.
However, Christian's casual bedside manner quickly gets under Tori's skin. She's anxious about Justin's upcoming surgery – which took all her energy to convince him to have in the first place.
After laying out all the options to Justin and Leah (Ada Nicodemou), he leaves the room – leaving Tori flustered, which Justin can't help but notice.
"Tori's nose is put slightly out of joint because he's very good at what he does, and confident. He's OK with people knowing that," Ditch explains.
Meanwhile, Justin continues to doubt whether he really needs the surgery. The procedure is risky and could paralyse him if anything was to go wrong.
"The thing about Justin's cavernoma is that surgery would mean cutting out the tumour," James, 44, tells TV WEEK.
"But because it's so close to the nerve, there's a chance they could unintentionally cut part of the nerves, which means he could lose his mobility. They can cut it out or use medication to reduce the size of the tumour and bring the swelling off the spine."
When his daughter Ava (Alice Roberts) comes to visit, he puts on a brave face and assures her there's nothing to worry about.
Meanwhile, Leah uses the youngster to convince Justin to have the surgery – until she's caught out.
"Leah thinks Justin should have the operation and not muck around with something like this," James explains. "But Justin, in his machoism, thinks he can just wait it out and it will fix itself."
On the beach, Justin and Ava play soccer to forget about everything. There are plenty of laughs as Justin rallies for a fun day with his daughter.
Just as she's about to head home, Justin holds Ava for what could be the last time...