[This content is out of date and no longer canon]

This is a part of their story that I’m still developing, so I’m sorry that I can’t give a more detailed answer, but Cypress likely found out ‘through the grapevine’ so to speak. Most of the Champions of the regions keep in touch, so Iris and Lance know each other and trade news about their families as well as what is going on in their respective regions. Iris is aware of her son’s poor relationship with Draco, so she tries to avoid talking about him when Cypress is around, but accidents happen. It’s likely that Cypress overheard that Draco has a son and though he initially would react with disinterest (why would I care what he’s getting up to?) his curiosity would get the better of him and he would want to try and find information on his ex’s child.

Cypress finds a picture of Noel either through social media or a mutual acquaintance and can’t deny the similarities he shares with the child, not to mention that doing the math puts Noel’s conception right around when he and Draco were still in a relationship. While I know Cypress definitely reacts poorly to the revelation, the details are still not entirely worked out, so I can’t say what exactly he does. I do know that he and Draco are able to come to a resolution eventually, where they agree to give Noel the option of contacting Cypress when he’s old enough to understand the situation. Whether or not Noel decides to do this is still unknown, however, since his character right now pretty much amounts to ‘Draco’s drama baby’, haha!