There is one thing that you need to understand. Player control their own charactors. If you try to control another charactors actions that is GOD MODING. Other writers will not allow that!
If you wish to share an action with an other player try a NPC (Non PLaying Charactor). Just make sure both or all of the player understand what is going on.
As for charactor development, that can come in time as you write a chractor more then once. Or as your thread develops, we learn more about the charactor. Allso, some writers but a basic bio of there charactor at the start of a story.
Does any of this help?
He smiles, he looks, he ran his fingers through her hair, she was beauty, not of our time, but the past.
A pirate life, that's what I want, oh to be on the sea, and hear the cannons roar!
You know you have it good. When the best ass on the beach is only half as good as what you have at home!
Once I sat by the sea, lived on a river, saw the main line of commerce, dwelling in a valley far from home.