As a DM I gave our dwarf cleric a bear cub as a companion, what can I do?

So I’m with 2 PCs, playing D&D essentials kit. Most of the time we follow the plot, add some extra things there and here and of course doing some improve. I try to stick to some of the rules but not always, to make it more fun.

The PCs recently encountered a big brown bear and killed it. A bear cub appeared and they managed to persuade the cub to go with them and they have it now. I applied wolf stats to it (didn’t give them the card yet, should I?). So now I’m thinking what this bear could do. I do not want to mobilize it as a fighting companion but make it more passive in battles and just help them with it’s perception and some other goodies.

I was thinking:

  1. Make the bear cub not grow with time, but rather give them an item to make the bear stronger in terms of constitution.

  2. It mostly follows them and will not run away on it’s own unless it’s in life threatening danger.

Edit: Question: Do my two points make sense and what stats should I include any other mechanics that would work with this relationship between dwarf and bear? Should I allow mounting of the bear once it grows?

edit2: what stats and info can i reveal to my PC?

If a dwarf barbarian wears heavy armor how fast do they move?

Quoted from d20:

Base Speed: (Slow and Steady) Dwarves have a base speed of 20 feet, but their speed is never modified by armor or encumbrance.

and

A barbarian’s land speed is faster than the norm for her race by +10 feet. This benefit applies only when he is wearing no armor, light armor, or medium armor, and not carrying a heavy load. Apply this bonus before modifying the barbarian’s speed because of any load carried or armor worn. This bonus stacks with any other bonuses to the barbarian’s land speed.

So a dwarf can never be slowed by any kind of armor, but barbarians lose the +10 feet of movement when wearing heavy armor.

Which takes priority over the other?