Hi, C.:
When you took the marker away from him, did you give him a choice to give it up?
You give him choices for everything.
You tell him: You have a choice, you can have the marker if you sit at the table, or if you get up from the table, the marker stays on the table, it's your choice.
In all situations you give him a choice.
You are teaching him to think and make the correct decisions.
The problem is: You have to make sure you have his attention.
When he acts out with his temper tantrums, you give him a choice. If you keep crying and screaming, I am going to put you in your room until you can
tell me why you are crying and screaming. You have a choice, stop crying or I will put you in your bed.
You might have to swat him on his hiny to make him stay in his bed.
Once he learns you mean business then he will pick the right choice.
Good luck.
D.