This player isn't the problem: your expectations mismatch is the problem
It looks like you each are looking to enjoy the game for slightly different reasons 1- your enjoyment looks to favor immersion and in-character play. You feel like you have to force the issue ...
I'm worried that I'm going to have to start punishing him for
basically doing nothing
and so you ask:
Any advice to try to get someone like Bob into the RP aspect of the
game before the DM hammer has to come down?
I answer: change your attitude as a DM.
This is a friend of yours, as you say, and you have taken the position that you need to force him to have fun the way you think it ought to be. This may be unintentional, but that's the signal that's coming across the wires.
Stop yourself, and step back a bit.
The four of you may need to get on the same page about what you each want out of this game together. A Session Zero is where you all make an input regarding what you hope to get out of the game (details at the linked Q&A). You may find out that each of your players have somewhat different expectations than you do -- which is fine. Talking to each other about it and arriving at a compromise goes a long way toward curbing your current frustration.
On-line RPG has some obstacles that 'in the flesh gaming' does not
I love to play in the flesh RPG games, but my current set up has me playing more over Discord or ROll20. I have found some significant obstacles with the on line tools, even though they are a great way to play with friends who are all over the world/map.
- You lack the immediacey of the "at a table" social context
- Visual cues, and some subtle vocal cues, are often missed.
- Play is a bit slower than in the flesh
People can tune out or wander off and it takes a while to figure that out. At a table, getting up and leaving is rather obvious.
All of these drawbacks amplify the disconnect between your player and you in terms of how much engagement with the fictional world that you expect (more) and he expects (little). It is easier to get and provide feedback in person since all cues are available.
Paladins are driven by their oaths, not by gods, in this edition.
I'd suggest that you take a look at the PHB and this Q&A to better understand how paladins work in this edition. You are however correct from an "in universe" aspect: choosing an oath will inforom the PC's RP from that point on. Where you may be making a mistake is in trying to force it.
Let the player grow into RP at their own pace
Forcing RP is a real turnoff. (This from experience in both direction, as GM and as player). Trying to force immersion just doesn't work. Encouragement of both is the better approach.
Related Q&As about encouraging Role Playing
How to get the players to care and RP more?
How to introduce and encourage role playing in non-roleplayers?
How can I encourage my D&D Encounters group to do more role playing?
How do I transition my players from roll-playing to role-playing?
You mentioned in a comment:
I'm rather imaginative and tend to try to push people when I fell that they are not participating. Really what the problem boils down to is that I want to try to get him more immersed in the game, but need advice as to the best route to do that.
Each player will seek, and enjoy, immersion in-game at a different level. Your encouragement to increase immersion will be improved in play by asking questions of the character when they take an action, and by describing how the world reacts to the character's decisions:
You may find some more usef techiques for encouraging "in character" behavior in this Q&A.
I'm all for PCs doing as their players see fit, and honestly any RP
from him is better than none, but the problem is that he is a level 2
Paladin. Next level, that is coming fast, he is going to have to take
his oath. Paladin is a class that requires a lot of RP to satisfy his
god and I'm worried that I'm going to have to start punishing him for
basically doing nothing, which I believe will turn him off of the
In my experience, you believe correctly.
If you want more RP out of this characer use the carrot, not the stick. Encourage this player to engage more "in game" and above all ...
You can't force fun.
1Notes on play styles and how people engage with a role playing game:
- There's a summary of Robin Laws' fine description of player styles here
- You will also find in the Dungeon Masters Guide (p. 6) a breakdown of ways that players have fun by engaging with the game. Not all styles mesh perfectly.