Disgraced student Ryan has lied and stolen from his mum Michelle (Kym Marsh) since returning to Weatherfield last month.
"His head is all over the place - he's not being himself at the minute," actor Heras told Inside Soap.
"But Ryan loves his mum to bits, so I don't believe he could ever harm her."
Worried Michelle discovers that Ryan's drug use has continued in next Thursday's (August 30) episode, after he sells tickets for a gig to Sophie to pay for cocaine.
However, Heras believes that Ryan's problems will continue to worsen, adding: "Who knows what he'll involve himself in next? It will take a big shock to make Ryan realise things have to change."
> Coronation Street Sol Heras: 'Things could get worse for Ryan'