|Behind the scenes|
- "I don't understand all of this, Jake. I don't really know what happened to your parents. But until they come back... or... well, I want you to consider yourself part of our family."
- ―Walter to Jake
- "As long as Visser One is in charge, no negotiation is possible. He wants total control of Earth and everyone on it. If another visser comes into power, that might change. Maybe. But right now, we've got to deal with this reality."
"There are other vissers? Would it be possible to tell Visser One we'll negotiate, but not with him?"
"I don't mean to sound condescending, Walter. But you have no idea who we're dealing with. If we approach Visser One for any reason, he'll kill us. Period. If we're lucky. If he stops to think, he'll probably torture us first. Just in case we've been holding back any useful information."
- ―Jake, Walter and Eva
After the Yeerks discovered that Animorphs were in fact humans and not Andalite bandits, the Animorphs had to evacuate their families. Walter and Michelle were the first to be told about the war and to be relocated to the Hork-Bajir valley. He and Michelle were both extremely interested in studying the Ax's and the Hork-Bajirs' physiology.
When the Animorphs decided to begin recruiting disabled children, Cassie disclosed the news to her father. Walter was appalled that they were using such children for war, but apparently did not tell anyone, as nobody else confronted Jake about the issue.
- On the Animorphs television series, Walter is named John.
- He is also referred to as "John" in earlier promotional materials such as Cassie's ID card and the Animorphs Alliance secret handbook.
- He is first referred to by name as "Walter" in The Diversion.