*scratch1*.el

(defvar adv-destination-room-overlay nil)
(make-variable-buffer-local 'adv-destination-room-overlay)

(defun adv-fontify-destination-room (s)
  (set-text-properties
   0 (length s)
   `(face (:foreground ,(format "#%02x%02x%02x" 30 30 30)))
   s)
  s)

(defun adv-delete-destination-room-overlay (&rest ignore)
  (when adv-destination-room-overlay
    (delete-overlay adv-destination-room-overlay)
    (setq adv-destination-room-overlay nil)))

(defun adv-create-destination-room-overlay (contents)
  (adv-delete-destination-room-overlay)
  (unless (save-excursion (goto-char (point-max)) (bolp))
    (setq contents (concat "\n" contents)))
  (setq adv-destination-room-overlay
        (make-overlay (point-max) (point-max) nil t t))
  (overlay-put adv-destination-room-overlay 'priority 100)
  (overlay-put adv-destination-room-overlay 'after-string
               (adv-fontify-destination-room contents)))

(adv-create-destination-room-overlay "Several\nLines\nHere")