In SharePoint Foundation 2013, I would like to create a SPD list workflow that takes different action based on the value of a custom column in the User Information List (keyed by who created the list item). It seems that the generally accepted solution is to request this additional data from the User Profile Service. However, as I am running Foundation, there is no Profile Service.
If I edit the "created by" column, I can choose to return the value of my custom column instead of the username information. However, I want the username information as well. It seems that there is a way to create some kind of "dependent lookup field" that can essentially duplicate the "created by" column but return the extra value I want, but I am not well-versed enough to dive this deep into SharePoint coding. It seems to me that this could be a powershell one-liner if I knew what I was doing.
Is this a viable solution? If so, how can I go about creating this column?