diff --git a/packages/behavior/context/index.js b/packages/behavior/context/index.js
index c70499e..28571fa 100644
--- a/packages/behavior/context/index.js
+++ b/packages/behavior/context/index.js
@@ -62,14 +62,17 @@ class Context extends Map {
     if ('key' !== first.type) {
       throw new TypeError(`First step in a traversal must be type "key"`);
     }
-    return rest.reduce((walk, step, index) => {
-      return this.takeStep(walk, (walk) => {
-        return fn(walk, step, index);
+    let previousNode = null;
+    return rest.reduce((node, step, index) => {
+      return this.takeStep(node, (node) => {
+        const result = fn(node, previousNode, step, index);
+        previousNode = node;
+        return result;
       });
     }, this.get(first.key));
   }
 
-  traverseOneStep(steps, node, step) {
+  traverseOneStep(steps, previousNode, node, step) {
     if ('undefined' === typeof node) {
       const rendered = this.renderStepsUntilNow(steps, step);
       debug(`"${rendered}" is traversed through but undefined`);
@@ -80,17 +83,17 @@ class Context extends Map {
         return node[step.key];
       case 'invoke':
         const args = step.args.map((arg) => arg.get(this));
-        return fastApply(null, node, args);
+        return fastApply(previousNode, node, args);
     }
   }
 
   traverseRaw(traversal) {
     const {steps, value} = traversal;
-    return this.traverseAndDo(steps, (node, step, index) => {
+    return this.traverseAndDo(steps, (node, previousNode, step, index) => {
       const isLastStep = index === steps.length - 2;
       // Traverse if we're not at the final step with a value.
       if (!isLastStep || !value) {
-        return this.traverseOneStep(steps, node, step);
+        return this.traverseOneStep(steps, previousNode, node, step);
       }
       // Try to set the value.
       switch (step.type) {