I think that just about sums up the API, requesting comments from everyone before I start implementing it.

api/src/main/java/net/md_5/bungee/api/connection/ProxiedPlayer.java

@@ -1,11 +1,52 @@
 package net.md_5.bungee.api.connection;
 
+import lombok.Getter;
+import lombok.Setter;
 import net.md_5.bungee.api.CommandSender;
 
 /**
  * Represents a player who's connection is being connected to somewhere else,
  * whether it be a remote or embedded server.
  */
-public interface ProxiedPlayer extends Connection, CommandSender
+public abstract class ProxiedPlayer implements Connection, CommandSender
 {
+
+    /**
+     * Name displayed to other users in areas such as the tab list.
+     */
+    @Getter
+    @Setter
+    private String displayName;
+
+    /**
+     * Connects / transfers this user to the specified connection, gracefully
+     * closing the current one. Depending on the implementation, this method
+     * might return before the user has been connected.
+     *
+     * @param server the new server to connect to
+     */
+    public abstract void connect(Server server);
+
+    /**
+     * Gets the ping time between the proxy and this connection.
+     *
+     * @return the current ping time
+     */
+    public abstract int getPing();
+
+    /**
+     * Completely kick this user from the proxy and all of its child
+     * connections.
+     *
+     * @param reason the disconnect reason displayed to the player
+     */
+    public abstract void disconnect(String reason);
+
+    /**
+     * Send a plugin message to this player.
+     *
+     * @param channel the channel to send this data via
+     * @param data the data to send
+     */
+    public abstract void sendData(String channel, byte[] data);
 }