The behavior that should give you a clue that a person might be an online predator is:
He will do or say anything to show he cares or wants to meet in person.
This behavior can be a red flag, as it may indicate an attempt to manipulate or pressure someone into a situation that could be unsafe. While communicating online is not inherently dangerous, the eagerness to establish a personal meeting can be concerning, especially if it is accompanied by attempts to build trust too quickly or express excessive care. It's important to always prioritize safety when interacting with people online.