Example of how Drupal 7 view mode template variables are set

view_modes_example.module

<?php

function tlr_blog_preprocess_node(&$variables) {
  global $user;
  $node = $variables['node'];

  if ($node->type == 'tlr_blog') {
    $blog = new TLRBlog($node->nid);
    $account = $blog->get_user();

    // Set template variables here for all view modes.
    $variables['title'] = $blog->title;
    // ...

    // Set template variables for specific view modes.
    switch ($variables['view_mode']) {
      case 'teaser':
        // Something specific for teasers.
        break;
      
      case 'full':
        // Something specific for full nodes.
        break;
    }
  }
}