I am a really big fan of Eragon and am DM'ing a heavily homebrewed Tyranny of Dragons with a few friends. Should I allow one of them to bond with a dragon?

For those that don't know what eragon is, it's pretty similar to How To Train Your Dragon, except Eragon can telepathically speak with his dragon and can even see through her eyes, hear through her ears, etc. But he can't control her, the dragon has complete free will.

From a roleplaying perspective, that could be really fun if handled right. You could even extend it into a trial of worth for the character/party, with the bond as the reward and a potential draconic ally for the party to call on in its hour of need.

A few things to consider: 

1. A dragon pal is potentially a very significant gift depending on what dragons are like in your game - so what will you do for the rest of the player characters to promote equity? Doing cool, special things for your players is great as long as everyone gets a cool, special thing eventually.

2. Seeing through another creature's senses is usually reserved for targets of the Beast Sense or Find Familiar spells. Because this is an existing game mechanic, be aware of what a "freebie" dragon bond might mean for any wizards, druids, rangers, or Pact of the Chain warlocks in the party who have to expend resources or take certain level-up options to get the same benefit.

3. It sounds like you're just wanting to go the glorified pet route, but think about the implications of what this bond might have on future plot, exploration, roleplay, or combat scenarios. It's much easier to set boundaries before you introduce something to your players than to have to nerf it after they've played with it.

Would it be too overpowered to allow for the telepathy and senses as a constant to the Bonded, but if the dragon chooses to, they can establish a weaker link with the others of the party who the dragon has befriended. They also gain a gain resistance to the dragons associated damage type while within like 30 ft. or something.

If someone wants to have a pet dragon, they should play a Drakewarden Ranger.  It's not a true dragon, but it is much better balanced than having an actual dragon acting as a party member's goon.

There's a homebrew book called The Gamemaster's Book of Legendary Dragons that has a great Dragon Rider class. I would recommend checking it out if you want to incorporate dragon riding into your campaign. 

Quote from The_Summoning_Dark >>

There's a homebrew book called The Gamemaster's Book of Legendary Dragons that has a great Dragon Rider class. I would recommend checking it out if you want to incorporate dragon riding into your campaign. 

 Thanks I'll check it out.

Quote from 6thLyranGuard >>

If someone wants to have a pet dragon, they should play a Drakewarden Ranger.  It's not a true dragon, but it is much better balanced than having an actual dragon acting as a party member's goon.

 The dragon is not the party's goon. It has its own free will, being played by me as if I were a player. It makes it own decisions, has its own personality, and can't be controlled by the party.

If it's bonded to a player character Eregon-style, it's a goon, not an independent character.

Quote from 6thLyranGuard >>

If it's bonded to a player character Eregon-style, it's a goon, not an independent character.

 HAVE YOU READ THE BOOKS?!!! Saphira is more like a best friend than a goon. She chose to follow Eragon when their opinions and goals aligned. If she disagreed with Eragon, she made it clear.