On his end as my emergency contact, how does he access my vault? Is my vault a tab within his vault, and is secure b/c he has to log onto his vault to get to my vault?
Hello @dbcriss1
Welcome to the LastPass Community!
I'll be happy to help you with your inquiry. In this case if you have already added your son as an emergency contact what will happen is that in case you forget your Master password or you need him to access he will request access from his own LastPass profile and depending on the time that you set as the waiting time he would need to wait for the backup of your account be transfer to him.
Or if he requests access but you still can view your vault it is possible for you to reject the access request so it will only be available when you lose access to your account. For more details you can review the article: Set up and manage emergency access.
Please let us know if you might need any further assistance.