Walter intentionally gives Travis the money to bother Ruth.
Explanation:
From the scenario, after Ruth refuses to give Travis the money he requests, and Walter doubled it, it seems that Walter wants to annoy Ruth in some way. This is the reason he gives Travis double of the amount he requests. This intentional provocation depicts the unhealthy relationship between Ruth and Walter. As a family, husband and wife should act in unity. They should discuss issues and agree with each other and even include their son in the discussion as part of a teaching moment to educate Travis. Had there been good relationship between Ruth and Walter, perhaps, Ruth would not have refused to give Travis any money. She could have explained to Travis that they had already planned to give him much more than he requested in order to cover his expenses.
I don’t have prior knowledge to the store but we can predict that something incredible and potentially bad has happened due to the way the writer described how the character said his words and the part that says “as I wished it twisted my hand like a snake”