How can I have both Participants Custom Data and Contacts Custom Data in a Drupal View
You need to add the Relationship (click open the Advanced fieldset on the right side in your View) to bring the Contact data to the party. 

Here's how:


Create a View: Show CiviCRM Participants
Relationships: add CiviCRM Contributions: Contact Record ID 





That will bring the entire CiviCRM Contact with custom fields to the party